I'm not an expert in this topic - I've just read a few books and shipping was covered in a few of my upper division classes.

They are the most important factors in the context of reliably shipping goods from port to port. If there was a sail technology that allowed reliable transit, predictable speeds and times (really slow is OK, a little late is not), and didn't cause an increase in other costs (say, insurance or maintenance), and could move the tonnage involved (up to 40 tons per container multiplied by thousands of containers, or enormous dry goods loads), I suspect it would capture a sizable portion of the market.

Edit: it occurs to me that significantly reducing fuel costs would allow entirely new kinds of loads to be transported and potentially radically alter the world economy. I once saw a chart where the Y axis was price per unit and the X axis was unit density. There was a line on the chart, above which it is economical to ship a good, below which it is not. The top right of the chart had things like electronics - which have been shipped since the dawn of the industry. The bottom left had things unprocessed ore, which have never made sense to ship.

> The bottom left had things unprocessed ore, which have never made sense to ship.

China mines and ships bauxite from Fiji to China.

https://aluminiuminsider.com/bound-chinese-shores-fiji-ships...

Without knowing much of anything: Bauxite is a bit special in that aluminum processing is extremely energy intensive, and I think the ore is often shipped to places with low electricity prices.

It is one of the bigger industries in Iceland: https://www.nytimes.com/2017/07/01/us/politics/american-comp...

This is a good question, and almost pure sail power may become a thing in the future. It looks like Maersk is trying to get ahead of the switch to cleaner fuel coming in 2020, which will increase their fuel costs by about 60%. This idea of putting sails on a large ship was at best only marginally cost-effective before now.

Some practical considerations come into play - while saving money is good, being able to reach your destination when you say you will is also worth something. With pure wind you lose that control. Deck size is not infinite, so there is a limit to how many sail towers are useful. Tower height also has practical limits before it destabilizes the ship. Handling bad weather is much easier with the on-demand power that comes from engines.

Why not use electrical propulsion and charge batteries from wind and solar? At first, as a fuel saving measure in optimal conditions (rely on internal combustion engines most of the time). Seems better than pure sail power, even though that is more efficient (due to direct wind to motion conversion).

Re:solar - there was an experiment where they covered a whole tanker with solar panels. During the day, they provided 10% of power....needed to run the lights on the ship.

Solar is just nowhere near good enough compared to the needs of a massive ship like this.

Wind would maybe work, but then remember that a turbine would effectively slow you down as you'd be pushing against the air.

The solar doesn't necessarily have to be ON the ship. If photovoltaics continue their process of price drop in STC $/W ratio, or if at some point very high efficiency low cost nuclear becomes economical, it will be possible to crack hydrogen from sea water at a shore based facility and compress it into tanks. Then use that to power massive fuel cells on ships with fully electric azipod drives.

If your $ per kWh is something ridiculously low like $0.002 you can economically electrolyze h2o to pure hydrogen.

The surface area of the ship, don't care about that. A 20x20km area of the Mojave desert covered in super low cost PV can provide the power needed.

This is the same economy of scale thing as a solar powered car. If you were to theoretically cover every square cm of a Tesla model S in high efficiency PV, and let it sit in the sun all day, it might take a week or more to collect the 95kWh needed to charge it fully. But if the PV is somewhere else on rooftops or otherwise-useless arid land, connected to the grid, you can plug your car in to a 240V 30A socket in your garage and charge it every day.

At perhaps 100 watts per square meter, a Maersk triple E ("An arbitrary large ship") at approximately 400 meters * 60 meters would generate 2.4 megawatts peak, or perhaps 400 kilowatts averaged.

This is not nothing. It's roughly as much power as a redlined sports car engine. It might be sufficient to fight the worst ocean currents, since propulsion power scales so frighteningly faster than speed.

https://www.maritime-executive.com/editorials/the-future-ult...

It would also make sense, with larger ships, to just implement the nuclear tech we already have.

> nuclear ships

IANA(nuclear scientist) but I imagine that it has to do with the lack of nuclear engines available for the commercial market, which is due to nuclear technology being restricted by export controls and the like. Keeping nuclear engines and fuel out of the hands of others is much simpler when they're only on military ships with armories and soldiers, basically impossible on unarmed, undefended commerical shipping vessels.

Do correct me if I'm wrong ...

> This is not nothing. It's roughly as much power as a redlined sports car engine.

And a sports car is what, 3,000 pounds? A container ship is something like 200,000 tons. I guess they can power a redlining sports car engine when out to sea but not a whole lot else.

It doesn't take an enormous amount of power to move a big ship very very slowly; Froude's law, the first approximation of the relationship, scales power requirements with velocity squared.

A Maersk Triple E has two up-to-30MW-each engines and a design speed of 19 knots. You'd scale down speed by a factor of 12 to achieve 1.6 knots (0.8m/s), and out of that you would get to scale down power by a factor of 144 to meet your ~400kw solar power endowment.

The question is whether you can cross the most powerful currents, and at 1.6 knots you would certainly need to be cognizant of them to stand a chance, but you could ford them in the manner of fording a river: Get pushed downstream a bit, but cross the highest velocity area perpendicular.

http://www.aoml.noaa.gov/phod/gdp/images/climatology.jpg

The Maersk Triple E and huge bulk carriers are practically worst-case-scenarios for solar, because there's so much ship to displace water under every square meter of solar. A smaller lighter catamaran is likely to find itself with dramatically higher speeds, albeit not linearly higher with hull depth, since a longer waterline is more efficient.

I'm not suggesting this is practical. I think massive nuclear powered cargo ships capable of high speed is a hell of a lot more practical in a post-carbon world. But again: it's not nothing.

Wind is also extreemly limited. As a ship scales up there is proportionaly much less wind energy to work with. Cargo ships move as fast as windsurfers (25+mph). Think of a windsurfer's sail to hull ratio. And the ship isnt on a plane, but pushes through the water. I see 1000' tall mast(s), with sails the size of small towns.

A big cargo ship's engine can be 25000kw. The biggest wind turbines (750') generate about 8000kw. So.. three of them? The ship would need to be 1500 feet long just to make room. But the wind isnt constant. Five turbines? Bridges might be an issue.

>As a ship scales up there is proportionaly much less wind energy to work with.

It's the square-cube law in operation. It also applies to solar. The only application of solar mounted on a transportation vehicle that makes any sense is those ultra-light unmanned planes that cruise above 60,000 feet.

Solar panels on cars make sense. They may not provide much actual charging, but they can prevent discharge over time.

I meant in the sense of providing the power for the motor.

I've long imagined some fun possibilities for this.

I picture a small-ish shipping ship, say something moving 20 or 30 containers only, fully autonomous (100% crewless) with sails and solar only powering it. Solar electric motors handling the near-land operations and "not enough wind" conditions, sails otherwise. If you had autonomous loading and unloading, you would have zero variable/operational cost.

I am certain there are very good reasons this would never work, but I still love the idea.

Unless someone has spent time at sea they cannot appreciate all the maintenance a large ship requires. Crewless ships are pipe dream. But captainless ships, ships operated without officers to navigate them, are a real option. You keep the tiny crew for fixing things but the operation of the ship is handled from afar.

Crews are cheap. Ships' masters are not.

Alternatively, the repair crew don't stay on the ship. Have a mobile team on a faster boat going ship to ship rescuing and repairing ones that can't make it to port again.

Maintenance is not repairs. The work needed to prevent repairs has to happen ever day. A crew at sea doesnt sit around waiting for an alarm. They are tending to equipment, verifying sensors ... even touching up paint is an essential daily task.

Interesting perspective. I hadn't considered that.

Part of me starts to wonder now about building boats that are more resilient, but then I remember that salt water is terrible and surely by now someone would have if it were possible, since we spend so much money on humans doing that maintenance!

If man can build it, the sea will destroy it.

Spoken like a true sailor :)

If you've ever been on a cruise, you'll notice the "crew" (not the staff) constantly painting and maintaining -- even on a brand new ship. If you ask, they'll tell you that they have to constantly work on the upkeep because of the size of the ship (kind of like painting the golden gate bridge, once you're done it's time to start over again).

The reason autonomous/crewless isn't really feasible or worth investing in is that most container ships only have a crew of about a dozen, and they are generally from low-wage countries so that their salary costs are far out-weighted by the fuel.

Maybe a little bit picky, but the average size of a crew on a, say, 9000 TEU container ship is actually closer to two dozen. 20-24 most of the time.

The number can rise further with more complex cargo.

I think this is a good example where automation doesn’t mean getting rid of all jobs, just 99% (which has nearly the same effect). I mean, we still have blacksmiths hand forging swords ffs.

Funny, I had this idea around my head for a while tagged under the "world changing startups I'd like to try someday" :)

I think it will do to shipping what two engine, midsized passenger jets (A350/787) are doing to air travel: connect directly between small ports anywhere, instead of using very large ports as hubs. FedEx/UPS could have sea terminals anywhere, possibly automated.

Global shipping will only grow and I don't see a driver for air freight prices to drop enough so that things are truly international (e.g. buy a fridge from AliExpress).

I think it needs to happen, and will happen.

Another fun possibility: a train of such ships connected by cables, which wind and unwind generators as the distances between them change, to power propulsion.

As for very good reasons why this would never work, sometimes that is beside the point. I am not in the running to redesign trade and power on my own terms, but sometimes I can flush out assumptions that don't need to be held.

No hostages for pirates to take either (though I guess they could help themselves to all of the goods on the ship)

And the ships. Drop an anchor and demand ransom to cut it free.

Even easier, just spoof the GPS signals with your own higher powered broadcast and make the ship think it's sailing around while it's actually stationary. Cant find the link but, some university actually demoed this working in real life with an actual container ship.

Im imagining an LED throwie type big magnetic thing with gps RX and TX, and a satellite uplink. Cruise by the autonomous ship on a jetski near a port, thrown the magnet thing on, jetski away, disrupt from afar once the boat is out at sea.

Ye old compass and lag wont get fooled by such mischievous act.

Electromagnet.

When the Cutty Sark was the state of the art in merchant shipping, the steam ship was becoming a thing. The steam ship was much slower than the Cutty Sark and needed its own fuel to operate. It's a good example how the numbers alone don't necessarily add up for new technology.

Fun trivia: when windjammers were going out of style, some businessmen still bought them for the low cost.

https://en.wikipedia.org/wiki/Gustaf_Erikson

For a while in 1930's small Åland had the largest sailing fleet in the world.

Slow is OK, but it must be exactly predictable. Don't be early, don't be late.

So you can use sails to help, but if you rely on them you might be late.

You can keep the timetable no matter what -- use sails just to save fuel consumption when weather is favorable.

I read an article about the potential of drone ships that claimed one reason ships don't go even slower is the logistics around having a crew on the ship for the entire voyage.

Capital expenditures are also pretty important. If the ships cost twice as much to build, you're paying twice as much in interest (or more). At the same amount of investment, you're shipping fewer things more profitably, and that only really makes sense if you can get attractive debt terms under pretty intense price pressure.

I wonder: do sails alone generate enough power to move today's massive container ships? Or would the ships need to be smaller?

There's no question sails can move today's cargo volume. But the shape of the ships doesn't lend itself to sail power. I think these sails are specific to supporting other power. And the shape of today's ships is very much towards fitting more cargo. I think you'd need at least slightly bigger ships that are efficient for sail power alone, and able to carry similar cargo volume or mass.

I think such rotating sails could be almost called 'solid state' - basically zero hassle compared to a traditional canvas where there is always person on lookout, trim before wind picked up, make sure rigging is maintained, etc. That said these probably produce way less power.

Rotating sails and wind turbines have historically been extremely high maintenance due to the forces the long moment arm puts on the rotational coupling at the base.

unpredictability of wind, i'd imagine.

That and storms. You need engines to ride out or (better) avoid storms at sea.

Is a ship that big bothered by anything less than a hurricane?

I would think so, certainly of you add masts and sails that can propel that big a ship.

Example without sails: https://en.wikipedia.org/wiki/MSC_Napoli:

”during European windstorm Kyrill, severe gale-force winds and huge waves caused serious damage to Napoli's hull, including a crack in one side and a flooded engine room

[…]

the earlier grounding in 2001 did not contribute to the loss”

That ship was 62,000 tons. That’s not huge by today’s standards, but not small either.